Production of preservative wood impregnants



Patented July 28, 1942 PRODUCTION OF PRESERVATIVE WOOD IMPREGNANTS Jacquelin E. Harvey, J r., Atlanta, Ga., assignor of one-half to Southern Wood Preserving Company, East Point, Ga., a corporation of Georgia Application July 13, 1940, Serial No. 345,437

Claims.

This invention relates to the production of valuable liquids from liquid and solid hydrocarbons.

More specifically the present invention relates to the production of oils of the wood preserving type from liquid and solid hydrocarbons.

An object of the present invention is the inducing of toxicity, in the manner hereinafter described.

Another object of the present invention is the induction of toxicity by aid of catalysis.

Yet another object of the present invention is the induction of toxicity in hydrocarbons having little or no toxicity, by the aid of catalysis, and providing means for sustaining said catalysis at optimum conditions.

Still another object of the present invention is the improvement of toxicity in hydrocarbons having toxicity.

Another and more specific object of the present invention is the conversion of aromatic tars, substantially in their entirety, into oils of the wood preserving type, wherein said conversion oils are more toxic than the parent tar.

Other objects of the present invention will be apparent from the following disclosures.

In the process of subjecting tars or fractions acted as an impediment to further toXicity-in- I duction.

It is now found that when attempting to catalyze, in certain manner, said toxicity induction, even though the toxicity-induction impediment was eliminated, at least to a degree, that said toxicity-induction became, after a time, a reduced quantity compared to the initially catalyzed increment of toxicity.

The invention will be understood from the following description of illustrative steps comprising various methods of securing the objects of the invention, when read in connection with the accompanying drawing wherein the figure is a diagrammatic sketch of an apparatus for carrying out a form of the process of the invention and wherein the nature of the step carried out in boiling substantially 15% at 355 C. was subjected to the action of hydrogen at 400 C. and 250 atmospheres'pressure for 8 hours. It was determined that the induction of toxicity reached a peak value and then became a reduced quantity. Research disclosed that as toxicity was induced, said toxicity increment acted as a blanketing efiect on further toxicity-induction. Removal of said toxic increment, at least to a degree, reinstated, at least partially, the initial high rate of toxicity synthesis.

Having determined the cause of toxicity-synthesis reduction, it was then attempted to catalyze the toxicity-inducing reaction. To this end, said starting material was charged to a hydrogenating unit under 250 atmospheres pressure and 400 0. temperature. Catalyst molybdenum sulphide. At the end of the second hour the hydrogenated mass was removed from the reaction chamber and stripped to 270, whereby to remove, at least to a degree, toxicity blanketing conditions. The stripped residual material was returned to the hydrogenating system under identical conditions and the run continued for such a time as to induce in the material under reaction a low end conforming to any of the several specifications for a wood preserving oil, as for instance, any of the following specifications, or others:

Wood preserving oils Identification: Initial po t American Wood Preservers Association 1% at 210 C. American Wood Preservers Association 5% at 210 C. American Wood Preservers Association 8% at 210 C. American Wood Preservers Association 10% at 210 C. American Wood Preservers Association 1 /2% at 235 C.

Prussian Ry 3% at C. National Paint Varnish & Lacquer Association #220 Southern Pine Shingle Stain Oil 5% at 137 C.

Neville Shingle Stain Oi1 I. B. P., 150 C.

After said low end as selected had been induced, the overall oil was usable as a wood preserving oil account its enhanced toxic properties, said enhancement flowing from the controlled action of hydrogen; or the wood preservative may be recovered as a distillate to serve as a substitute for conventional creosote, or the like; the residue from said distillation, if desired, being recycled. In the event low ends below a specification wood 5% at 162 C.

. recover a substitute for any of the wood preserving distillates currently on the market. As for instance, serving as a substitute for any of the following sepcifications, or others:

Specifications 1. American Wood Preservers Association 11. Up to 210 C., not more than 1). Up to 235 C.,not more than 25% 2. American Wood Preservers Association a. Up to 210 0., not more than 1% b. Up to 235 C., not more than 0. Up to 355 0., not less than 65% 3. American Wood Preservers Association a. Up to 235 0., not more than 1 /2% I). Up to 300 C., not more than Mi /2% 0. Up to 355 0., not less than 45% 4. American Wood Preservers Association a. Up to 210 C., not more than 8% b. Up to 235 0., not more than 35% 5. American Wood Preservers Associat on a. Up to 210 C., not more than 10% 5. Up to 235 0., not more than 40% 6. American Wood Preservers Association a. Up to 210 0., not more than 5% 1). Up to 235 0., not more than '7. Prussian By.

a. Up to 150 0., not more than 3% 1). Up to 200 C., not more than 10% 0. Up to 235 C., not more than 25% i 8. National Paint Varnish 8: Lacquer Association a. 5% at 162 C. b. 97% at 270C. Southern Pine Shingle Stain 011 a. 5% at 137 C. b. 95% at 257 C. 10. Neville Shingle Stain Oil 11.. I. B. P., 150 C. b. 5% at 205 C. c. 95% at 292 C.

From the foregoing specifications it will be seen that the end point of the accepted and specification wood preservatives 1s a somewhat indefinite point, especially in the several A. W. P. A. specifications. Thus, it will be noted that the wood preservative distillate recovered from the beneficiated material may have an end point as low as in the order of 250 C. or an end point of in the order of as high as 40 to 50% residue above 355 C.

Several lots of the named coal tar fraction were treated as aforenamed using identical catalyst, but the synthesis of toxicity did not continue at the initial rate even though the toxicity blanketing increment as aforedescribed had been eliminated, at least to a degree. Research disclosed the fact that the decline in toxlcity synthesis was due to, at least when using a sulphide catalyst, conversion of the catalyst, at least partially, into a form other than sulphide. It was found that the initial rate of toxicity synthesis could be restored, at least to a degree, by malntaining a hydrogen sulphide partial pressure of at least a fractional atmosphere. To this end, one half of one percent sulphur was added to the feed stock. Identical runs were repeated with the sulphur laden stock and thereafter toxicitysynthesis held without substantial reduction, in-

light of the 1 other than elemental; any form of sulphur capa-' ble of generating hydrogen sulphide under conditions of the present process. Generally, a hydrogen sulphide partial pressure of in the order of 1 atmosphere will be satisfactory; however, higher or lower partial pressure is usable.

Thus, the present process provides a method for the induction of toxicity, said induction characterized by subjecting a mixture of tar fractions in the presence of a sulphide catalyst, to the controlled action of hydrogen and hydrogen sulphide; when the rate of toxicity synthesisv declines because of blanketing efiect of newly induced toxicity, removing at least to a'degree, said blanketing effect and continuing the process on the stripped material.

Aromatic tars, or fractions thereof, serve as suitable starting material for the present process. Tars or fractions thereof, at least once refined by hydrogen are highly desired starting materialsinasmuch as they require less vigorous converting conditions.

Thus, the starting materials of the present process broadly include tars and fractions thereof, including high boiling hydrocarbons, wherein toxicity may be induced.

As is well known hydrogenations proceed at lowered temperatures and pressures. However, to approximate commercial necessities elevated temperatures and pressures are desirable. Temperatures as low as 250 C. and pressures as low as 50 atmospheres may be used, however, pressures in the order of 200 atmospheres or higher, and temperatures in the order of 375 C. and above are desirable.

The time element cannot be given as an arbitrary period because of varying qualities of the starting materials, and the initial boiling point of the conversion product.

By the term beneficiation as used herein and in the appended claims is meant the starting material at least once subjected tothe action of hydrogen and hydrogen sulphide in accordance with the present process.

From the standpoint of commercially available starting materials, tars derived from coal and petroleum or petroleum fractions, as for instance, coal tar boiling predominantly above C. and aromatic tars or extracts of petroleum origin boiling predominantly above 200 C. are attractive starting materials.

Example II .--A coal tar boiling predominantly above 190 C; was subjected to the action of hydrogen and hydrogen sulphide at a pressure of 300 atmospheres and- 400 C. Hydrogen sulphide partial pressure 1 /2 atmospheres. Catalyst, cobalt sulphide. Reaction time 30 minutes. The beneficiated tar was removed from the reaction zone and stripped up to 250 C. The stripped residual mass was returned to the reaction zone and treated under identical conditions except that a the temperature was raised to 450 C. Treatment was then continued for 1 hour. The material was then withdrawn from the reaction zone. Inspection disclosed it to have 19% boiling up to 210 C. The beneficiated material was then stripped of low ends to leave a material boiling 3% at 210 C.

The wood preservative recovered as a residue by stripping the low ends of the beneficiated material had a coke residue, specific gravity, viscosity and toxicity that made it acceptable as a substitute for a creosote-coal tar solution of A. W. P. A. specifications which are noted below:

a. It shall not contain more than 3% of water.

I). It shall not contain more than 2% of matter insoluble in benzol.

c. The specific gravity of the oil at 38 C. compared with water at 155 C. shall not be less than 1.05 or more than 1 .12.

d. The distillate, based on water-free oil shall be within the following limits:

Up to 210 C., not more than 5% Up to 235 0.. not more than 25% e. The residue above 355 C., if it exceeds 26%, shall have a float-test of not more than 50 seconds, at 70 C.

f. The oil shall yield not more than 6% coke residue.

The action of sulfur in the instant process may be further explained as also lowering the toxicity blanketing efiect of the residual materials boiling above 270 C. in the wood preservative impregnant.

The toxicity of a tar derived wood preserva- U tive is, as is known in the art, proportional to the percentage distilling below 270 C. Applicants researches have shown this to be true if other things are equal. However, other things are not always equal. preservative produced from a given material by the instant process will have a residual oil above 270 C. that has a toxicity blanketing effect of X; however, if a wood preservative be produced from identical starting material and under identical process controls while employing the instant process, but without sulfur, the wood preservative impregnant so produced will have a residual oil above 270 C. whose toxicity blanketing effect is X plus Y. Stated in another manner, the

preservatives made in accordance with the instant process have a greater toxicity than preservatives made by a similar process less sulfur.

Minor changes may be made without departing from the spirit of the present invention.

I claim:

1. In the production of a preservative wood impregnant the process which comprises: subjecting a mixture of tar fractions to the action of hydrogen in the presence of hydrogen sulfide and a sulfide catalyst with time, temperature and pressure so controlled as to induce new low boiling fractions with consequent reduction in rate of said synthesis; stripping from the treated material newly induced low boiling material to produce a residual with an initial boiling point in the range of about 250 C. to 270 C.; continuing reaction conditions on the stripped residual with resultant at least partial restoration of rate of said synthesis and with time, temperature and As an example, a wood pressure so controlled as to convert said residual into an oil of the wood preserving type which if relieved of a percentage of its low boiling fractions will have no greater percentage of materials distilling below a given temperature, nor a greater percentage of materials distilling between the initial point and a given temperature than is permitted by specifications accepted in the trade for a tar derived wood preservative and being further characterized by a substantialresidual above 300 C.; and relieving said treated residual of that percentage of low boiling materials to provide specification conformance as stated.

2. In the production of a preservative wood impregnant the process which comprises: subjecting a mixture of tar fractions to the action of hydrogen in the presence of hydrogen sulfide and a sulfide catalyst with time, temperature andpressure so controlled as to induce new low boiling fractions with consequent reduction in rate of said synthesis; stripping from the treated material newly induced low boiling material to produce a residual with an initial boiling point of about 250 C. to 270 C.; continuing reaction conditions at a more elevated temperature on the stripped residual with resultant at least partial restoration of rate of said synthesis and with time, temperature and pressure so controlled as to convert said residual into an oil of the Wood preserving type which if relieved of a percentage of its low boiling fractions will have no greater percentage of materials distilling below a given temperature, nor a greater percentage of materials distilling between the initial point and a given temperature than is permitted by specifications accepted in the trade for a tar derived wood preservative and being further character ized by a substantial residual above 300 C.; and relieving said treated residual of that percentage of low boiling materials to provide specification conformance as stated.

3. In the production of a preservative wood impregnant the process which comprises: subjecting a mixture of tar fractions to the action of hydrogen in the presence of hydrogen sulfide and a sulfide catalyst with time, temperature and pressure so controlled as to induce new low boiling toxic fractions with consequent reduction in rate of said synthesis; stripping from the treated material newly induced low boiling material to produce a residual with an initial boiling point in the range of about 250 C. to 270 C. continuing reaction conditions on the stripped residual material with resultant at least partial restoration of rate of said synthesis and with time, temperature and pressure so controlled as to convert said residual substantially in entirety into an oil of the wood preserving type having no greater percentage of materials distilling below a given temperature, nor a greater percentage of materials distilling between the initial point and a given temperature than is permitted by specifications accepted in the trade for a tar-derived wood preservative and being further characterized by a substantial residual above 300 C.

4. In the production of a preservative wood impregnant the process which comprises: subjecting a mixture of tar fractions to the action of hydrogen in the presence of hydrogen sulfide and a sulfide catalyst with time, temperature and pressure so controlled as to induce new low boiling toxic fractions with consequent reduction in rate of said synthesis; stripping from the treated material newly induced low boiling material to produce a residual having an initial boiling point in the range of about 250 C. to 270 C.; continuing reaction conditions at a more elevated temperature on the stripped residual material with resultant at least partial restoration of rate of said synthesis and with time, temperature and. pressure so controlled as to convert said residual substantially in entirety into an oil of the wood preserving type having no greater percentage of materials distilling below a given temperature, nor a greater percentage of materials distilling between the initial point and a given temperature than is permitted by specifications accepted in the trade for a tar-derived wood preservative and being further characterized by a substantial residual above 300 C.

5. In the production of a preservative wood impregnant, the process which comprises: subjecting a mixture of tar fractions to the action of hydrogen in the presence of hydrogen sulfide and a sulfide catalyst with time, temperature and pressure so controlled as to induce new low boiling fractions With consequent reduction in rate of said synthesis; stripping from the treated material newly induced low boiling material to produce a residual having an initial boiling point not in excess of about 270 C.; continuing reaction conditions on the stripped residual with resultant at least partial restoration of rate of said synthesis and with time, temperature and pressure so controlled as to convert said residual into an oil of the Wood preserving type distilling not in excess of about 3% at 150 C. and being further characterized by a substantial residual above 300 C.

JACQUELIN E. HARVEY, J R. 

